This invention relates to an improved liquid-phase concentrated sulfuric acid process for the indirect hydrolysis of an olefin to produce a lower aliphatic alcohol.
It is known to produce a lower aliphatic alcohol by reacting the corresponding olefin with concentrated sulfuric acid to form an ester reaction product and thereafter hydrolyzing the ester reaction product to form a lower aliphatic alcohol. This process is characterized by producing large quantities of dilute sulfuric acid together with some undesirable by-products. For this process to be feasible, it is essential that the dilute sulfuric acid be purified and concentrated so that it can be recycled to the esterification reaction.
It is also known to concentrate the dilute sulfuric acid effluent from this process by means of a direct heat immersion-burner unit. In addition to concentrating the dilute sulfuric acid, the immersion-burner effects a combustion of the undesirable by-products present in the dilute sulfuric acid effluent and thus purifies the sulfuric acid being concentrated serving to facilitate the recycling of the acid to the process.
A serious draw-back to the direct heat immersion-burner concentration step is that the environment in the evaporator or concentrator is very corrosive. The effective life of the direct heat immersion-burner is unusually short under the extremely corrosive conditions prevailing. Short immersion-burner life or early failure is, therefore, a serious limitation or bottleneck in this process.
An improved process has been developed which substantially reduces the immersion-burner corrosion problem and which is more efficient in the utilization of the heat energy input.